Angela tries to pick up a copper penny using a bar magnet, but the penny does not move. Then, she tries to pick up an iron nail using the bar magnet, and the nail lifts up toward the magnet. Her teacher tells her that the magnet lifts the iron nail because it is a ferromagnetic material. Which of the following best describes a ferromagnetic material?
a material made of non-metals that produce magnetic fields
a material that easily conducts electricity
a material with naturally strong magnetic properties
a material that produces its own magnetic field